Rectangularly shaped gas-filled lamp for photocopying machines

ABSTRACT

A rectangularly shaped gas-filled lamp for photocopying machines having a main portion bent at right angles at its ends. The bent ends have a larger radius at the outer surface than at the inner surface, and the inner surface has a reduced portion to decrease the cross-sectional area and provide more brightness at the bent ends.

United States Patent Inventor Appl. No.

Filed Patented Assignee Priority Walther von Grabe Koenigstein, GermanyApr. 30, 1969 Jan. 11, 1972 Kabushiki Kaisha Ricoh Tokyo, Japan Apr. 30,1968 Japan 43/2903] RECTANGULARLY-SHAPED GAS-FILLED LAMP FORPHOTOCOPYING MACHINES 1 Claim, 4 Drawing Figs.

US. Cl 313/109, 313/220 Int. Cl H0lj 61/30, H01 j 61/44 Field 01' Search313/109,

Primary Examiner- Roy Lake Assistant Examiner- Palmer C. DemeoAnorneyBurgess, Ryan & Hicks ABSTRACT: A rectangularly shaped gas-filledlamp for photocopying machines having a main portion bent at rightangles at its ends. The bent ends have a larger radius at the outersurface than at the inner surface, and the inner surface has a reducedportion to decrease the cross-sectional area and provide more brightnessat the bent ends.

RECTANGULARLY SHAPED GAS-FILLED LAMP FOR PHOTOCOPYING MACHINESBACKGROUND OF THE INVENTION The present invention relates to aphotocopying lamp and more particularly a gas-filledlamp best suited forphotocopy: mg.

Generally, the photocopying machine must be compact in size and easy tooperate so that it may be operated even in a small room. But suchmachine is not available at present.

There has been known a photocopying machine of the type in which anoriginal to be copied is not illuminated at its whole surface, but theoriginal is partially illuminated one portion at a time, sequentially,by a moving lamp until the whole surface is illuminated. However, it isdifficult to incorporate a tubular lamp in the photocopying machine ofthe type described because the electrical connection members areattached to the ends of the tubular lamp so that no light is emittedtherefrom. Furthermore, the light varies in intensity and color alongthe longitudinaldirection of the tubular lamp.

In the photocopying machine of the type described, because of thevariation in intensity and color of the light produced from the lamp,only the light emitted from a relatively narrower portion in thevicinity of the center of the lamp is actually utilized forillumination. That is, the substantial portions adjacent to the ends ofthe lamp, which also produce light, extend beyond the side edges of theoriginal. Therefore, extra space must be allowed outwardly of the sideedges of the original so that the ends of the tubular lamp may passfreely. However, such space is wasted as it is not utilized for otherpurposes. When the width of the exposure in the photocopying machine isequal to that of the space for mounting the tubular lamp, theconventional lamp having the construction as described above cannot beused. For these reasons, the photocopying machine of the type in which atubular lamp is movably mounted for scanning exposure is inevitablylarge "'1 size.

SUMMARY OF THE INVENTION In brief, the present invention provides agas-filled lamp for photocopying comprising a tubular main member forutilizing substantially all of the light produced. A tubular side memberis formed integral with the main member by bending at least one endthereof, and a bending member is provided between the main and sidemembers having a smaller cross-sectional area than those of the main andside members. The effective length of the lamp, that is the main member,is made equal to the length of the lamp effective for emitting theillumination lights to be actually used.

In one embodiment of the present invention having the construction asdescribed above, the bending member is bent to at least an angle of 90and the inner side thereof is reduced, thereby reducing itscross-sectional area.

In another embodiment of the present invention, the lamp is formedrectangular in shape so that a longer side constitutes the main memberfor emitting the required light and the electrical connection membersare attached in opposed relation with each other to the ends of the lampsymmetrical about the center of the longer side. The cross-sectionalarea at each end of the longer side, that is the main member, has areduced cross-sectional area by providing a reduced portion extendinginwardly from the inner side of the end portion of the main body. Theside member, that isthe shorter sides of the rectangle are made as shortas possible. The main member, that is the longer side, is coated withfluorescent or phosphor material and this coating is preferably extendedbeyond the main member up to the side members. Alternatively, thecoating may extend substantially beyond the center of the side members.

In a further embodiment of the present invention, the outer side of thebending member is rounded so that the outer generating line of the mainmember connects to that of the side member through the outer. generatingline having a large radius of curvature. This provides the same effectas that attained when the main member is extended linearly beyond thebending members. By reducing the inner side of the bending member theintensity of illumination at the portions in the vicinity of the bendingmembers can be increased.

The lamp according to the present invention can eliminate the defectknown as vignette effect.

One of the objects of the present invention is to provide a photocopyingmachine compact in size.

Another object of the invention is to eliminate the variation inintensity of light in the longitudinal direction of a lamp.

The above and other objects, features and advantages of the presentinvention will be more apparent from the following description taken inconjunction with the accompanying drawing.

BRIEF DESCRIPTION OF DRAWING FIG. I is a side view of one embodiment ofthe present invention;

FIG. 2 is a plan view thereof, viewed in the direction of the arrow IIin FIG. 1;

FIG. 3 is a perspective view of one example of the arrangement thereof;and

FIG. 4 is an explanatory view of another example of the arrangementthereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, thelamp construction includes a main member 10, two side members 12 and twoend members 14 coupled substantially at right angles to the side members12 and in parallel with the main member 10.

These members 10, 12 and 14 form substantially rectangular shape asshown in FIG. 1. The produced light is emitted from the side of the mainmember 10 which is coated with fluorescent material so as to produceafterglow as shown by the crosshatched portion in FIG. 1. The sidemembers 12 are positioned substantially at right angles relative to themain member 10, and at the bending portion 13 of the side member 12 areduced portion 16 is provided. As compared to the case when the bendportion 13 is formed as shown by the broken line 18 in FIG. 1, thereduced portions 16 serve to cause the filamentlike current to pass moreclosely to the outer surface 20, that is the generating line, of themain member 10. In order to control the light emitted from the mainmember 10, that is the intensity of illumination, the connecting surfaceconnecting the outer surface 20 of the main member 10 and the outersurface, generating line, of the side member 12 has a relatively largerradius of curvature as shown by a contour line 22. That is, the radiusof the connecting surface 22 is larger than that surface connecting theside and end members as shown by 26 or by a broken line 24.

The fluorescent coating is applied up to the boundary lines 28 betweenthe main and side members 10 and 12. This coating may be applied beyondthe center of the side member 12 so that the side member alsoadvantageously provides the light transmission.

At the ends of the end members 14 are attached electrical connectionmembers 30 each having a fixed knurled nut for connection to a cablehead of the wire.

The lamp having the construction described above with reference to FIGS.1 and 2 may be utilized for example as shown in FIG. 3. That is, in thisarrangement an original to be copied is placed upon a glass plate 36 andilluminated by a lamp 34. It is not necessary that outer end edges 38 ofthe glass plate 36 be extended beyond the outermost generating line ofthe side member 12. Alternatively, the edge 38 may be extended only alittle beyond the side member 12. The lamp 34 is mounted upon a suitablecarriage (not shown) and is moved in the direction indicated by thearrow 42 in parallel with the glass plate 36. If required a plurality oflamps 34 may be mounted upon the lamp carriage in side-by-side relation.When the lamp carriage is moved, the whole surface of the original isilluminated.

The fluorescent coating extending beyond the boundary line 29 (shown inFIG. 3), that is substantially beyond the center of the side member 12provides light emission as shown by the arrows 44. That is, the loss ofthe light emission that would be expected due to the main member notbeing extended is compensated by the arrangement of the lamp 34 as shownin FIG. 3 without adversely affecting the distribution and the intensityof the light.

Since the lamp 34 may be held in position by means of the connectionmembers 30, it is not necessary to design the length of the lampcarriage longer than that of the lamp 34.

By providing the reduced portion 16 in the glass wall, the bendingportion 12 will have a smaller cross-sectional area. The reduced portionextends toward the discharge space in the main member 10 at an angle of10 to 90, preferably 45, so that the gaseous discharge may be effectedin the main member 10 at a portion closer to the light emission portionthereof.

Another arrangement of the lamp of the present invention is shown inFIG. 4. Upon the glass plate 36 is placed a page of an opened book, Bowhich is illuminated by the lamp 34 for focus through lens L on copysheet ba. In this case, the rectangular side of the lamp 34 ispositioned substantially in parallel with the glass plate 36. Thisarrangement can prevent the peripheral portion of an image of the pageto be copied from becoming dark.

From the foregoing, it will be seen that the lamp carriage may be madesubstantially equal in length to the lamp so that much space can besaved, and the photocopying machine can be made compact in size andlight in weight. Furthermore, by a suitable arrangement of the lamp ofthe present invention in case of forming an image of an original by alens the peripheral portion of copy sheet may be prevented from becomingdark, that is the whole surface of the sheet may be uniformlyilluminated. The present invention has been so far described withparticular reference of the embodiment thereof, but it will beunderstood that variations and modifications can be effected withoutdeparting from the true spirit of the invention as described hereinaboveand as defined in the appended claim.

1 claim:

1. A gas-filled lamp for a photocopying machine comprising a pair oftubular side sections;

a tubular main member having a substantially constant cross-sectionalarea therealong, said main member having bent ends forming a continuousattachment to a respective side section, each side section extending atto said main member, said main member being coated with fluorescentmaterial, and said coating being applied to both said bent ends andterminating at said attachment to said side sections;

a pair of tubular end members, each equal in length and forming acontinuous attachment with a respective one of said side sections andextending at 90 to said side section toward each other and having endportions terminating in substantially close proximity with electricalconnections attached to said respective terminating end portions;

said main member, side sections and end members forming a substantiallyrectangularly shaped lamp, the length of each said side section beingsubstantially shorter than the length of either of said end members sothat said main and end members are located in close parallel proximityto each other;

each said bent end of said main member having an outer curved surfaceand an inner curved surface defining an end cross section areatherebetween, the radius of said outer curved surface being greater thanthe radius of said inner curved surface; and

said end cross-sectional area adjacent said inner curved surface havinga reduced portion so that said end cross-sectional area is less thansaid substantially constant crosssectional area along said main member.

1. A gas-filled lamp for a photocopying machine comprising a pair oftubular side sections; a tubular main member having a substantiallyconstant crosssectional area therealong, said main member having bentends forming a continuous attachment to a respective side section, eachside section extending at 90* to said main member, said main memberbeing coated with fluorescent material, and said coating being appliedto both said bent ends and terminating at said attachment to said sidesections; a pair of tubular end members, each equal in length andforming a continuous attachment with a respective one of said sidesections and extending at 90* to said side section toward each other andhaving end portions terminating in substantially close proximity withelectrical connectIons attached to said respective terminating endportions; said main member, side sections and end members forming asubstantially rectangularly shaped lamp, the length of each said sidesection being substantially shorter than the length of either of saidend members so that said main and end members are located in closeparallel proximity to each other; each said bent end of said main memberhaving an outer curved surface and an inner curved surface defining anend cross section area therebetween, the radius of said outer curvedsurface being greater than the radius of said inner curved surface; andsaid end cross-sectional area adjacent said inner curved surface havinga reduced portion so that said end cross-sectional area is less thansaid substantially constant cross-sectional area along said main member.